Thanks for your participation in this drop and joining in the product discussion. At the beginning of this drop, we asked for your input on the final details of the product and we got lots of great responses. From there, we took all your topics of interest to our manufacturing partner and discussed what could be done without impacting the expected delivery date. As initially expected, some changes were possible, some were not, and some could be solved in the future. Here’s a list of answers to the top questions ya’ll have been asking. Feel free to reply with any questions I missed, I’ll be around and answering questions all today.

Important points include the matte finish (as opposed to brushed), most lettering replaced with symbols, and the upgraded volume knob.

The matte finish for the front panel will look the same as the matte metal finish this O2 currently sports on all surfaces but the front panel.

The volume knob has been upgraded to a full metal option (as opposed to hollow metal and plastic) with rubber grommets for a smooth grip.

All these changes originated in this discussion section, thank you again for your support. If you find these design changes offencive and would like to leave the drop as a result, simply head over to: https://www.massdrop.com/transactions and cancel your order (third button down the right side of the screen if this is your most recent Massdrop purchase). We’ve extended the drop until tomorrow night so you can cancel your purchase any time between now and midnight Tuesday night (11:59pm PST tomorrow night).

220v Support:

Lots of people have been asking if this amplifier supports 220v power. The answer is yes, this amplifier does support 220v power, but you need a 220v power adapter. The adapters that ship with this drop will be a 110v US plug adapters. As such, anyone based overseas will need to get a separate power supply that fits their needs.

They’re very affordable at $10.99 from JDS labs: https://www.jdslabs.com/products/73/g-e-z-15vac-adapter-for-o2/

And if you prefer, you should be able to find cheaper alternatives at most electronic parts suppliers like Digikey, Mouser, or equivalents based in your country.

Additional Features:

In the course of this discussion we’ve seen tons of people requesting additional/different features like rear power input, rear RCA inputs, 1/4” headphone jacks, etc.

While we’d like to add options like this, our manufacturing plan for these O2s has a tight schedule and any major deviations from the original design would increase wait times meaningfully (changes proposed, plan re-done, contracts re-negotiated, etc). That said, a couple of community members brought up an interesting idea here in the discussion: Could Massdrop make DIY upgrade kits for these changes?

After talking it over with our manufacturing partner, the answer is yes. While they won’t be available until some time after this drop is fulfilled, we will be exploring making DIY kits as cheaply as possible for the most requested physical changes. Based on the discussion so far, our first priority will be a kit to give you the option of having a rear powered unit (new back plate, jumper wire, power jack). Additionally, we’ll be posting the parts list for all of these kits in this discussion as they’re finalized over the coming weeks. You won’t be seeing one every week, but we want to make it easy for people to source the parts themselves if they don’t want to wait for our pre-packaged solutions.

All things considered, I think it’s been an amazing drop. Your support, your questions, your concerns, all made for a better product and for that I say thanks.

I’ll be around if you have any additional questions, otherwise, you have until this drop ends at midnight Tuesday night (11:59pm Tuesday 8/4/2015) to make changes to your order.

Thanks for this Will. Could you also advice what amperage the power adapter should have? Does it have range? I'm trying to source one locally and that seems to be the only variance. If I can find one that matches I'm in.

Sadly not for this iteration of the drop. We plan to make 220v adapters available with future O2s (cost tbd but shouldn't be much more if any increase) but it won't be possible to swap them out or offer a discount this time around.

Will, the matte finish looks great! Is it possible for the next drop to be for a desktop version with rear power and rear RCA inputs, a 1/4" output on the front, and rubber feet? While I dig the DIY solution, these seem to the the most suggested/desired revisions that have been requested and it makes sense to take advantage of economy of scale.

Also, some lines around the knob and a mark on the knob to indicate the current volume level would be useful.

Sorry for the noob question but can the AC adapter that comes with the Massdrop O2 able to recharge 9V NiMH batteries or do I need a different AC adapter? If it is good to go would something like this work. http://www.amazon.com/SunLabz-300mAh-NiMH-Rechargeable-Batteries/dp/B00VSKZNHG/ref=sr_1_2?ie=UTF8&qid=1438632467&sr=8-2&keywords=9v+nimh

Will Thanks for the clarification. I've cancelled this drop only because a replacement 220V power pack could easily cost 1/4 the cost of the O2 itself here. Really happy you stuck to the original specifications and look forward to the next drop with Australia-friendly power packs as an option :) . Didn't have a problem with any of the other design choices as I think the original creator of the O2 was concerned with the technical aspects.

Thanks! Look forward to the second iteration ;) . Should have a set of Sennheiser HD-600s by then too.

For the record: everything with this was fine by me and it was just the lack of power pack option this time... and not actually having the HD-600 headphones yet (I may have been a tad eager to jump onboard so early :D ).

I have an idea regarding the 220v adapter issue. How about just creating a drop for the adapter itself? -- No need for identifying who's bought the O2, simply because people are gonna buy the adapter if and only if they have the O2 to go with it.

I'm still waiting for these DIY kits you mentioned that you would offering during the first drop of this O2 amp. You stated: "Based on the discussion so far, our first priority will be a kit to give you the option of having a rear powered unit (new back plate, jumper wire, power jack)." I'm also quite interested in an ODAC kit for this O2 amp too. Could you please give us an update on when these DIY kits will be offered.

In the first drop of this O2 Amp you said "we will be exploring making DIY kits as cheaply as possible for the most requested physical changes. Based on the discussion so far, our first priority will be a kit to give you the option of having a rear powered unit (new back plate, jumper wire, power jack). Additionally, we’ll be posting the parts list for all of these kits in this discussion as they’re finalized over the coming weeks. I'm still waiting on these DIY Mod Kits, from the first drop, could you please let us know when we can get these DIY Kits.